fix: do not throw when Rule.layer (vuejs#2000)

Related to vuejs#1849 but this PR doesn't fix the problem that `component.vue?type=style` doesn't inherit the layer.
It only ensures that webpack does not throw, and all existing usages aren't broken by `vue-loader`.

Author: nolimitdev

src/pluginWebpack5.ts

@@ -90,12 +90,14 @@ const ruleSetCompiler = new RuleSetCompiler([
   new BasicMatcherRulePlugin('realResource'),
   new BasicMatcherRulePlugin('issuer'),
   new BasicMatcherRulePlugin('compiler'),
+  new BasicMatcherRulePlugin('issuerLayer'),
   ...objectMatcherRulePlugins,
   new BasicEffectRulePlugin('type'),
   new BasicEffectRulePlugin('sideEffects'),
   new BasicEffectRulePlugin('parser'),
   new BasicEffectRulePlugin('resolve'),
   new BasicEffectRulePlugin('generator'),
+  new BasicEffectRulePlugin('layer'),
   new UseEffectRulePlugin(),
 ])